.puke-tips{
  text-align: center;
  font-size: 18px;
  color: #fff;
}
.puke{
  width: 400px;
  margin: 20px auto;
  transition: transform 1s;
  transform-origin: center center 0;
  li{
    float: left;
    width: 100px;
    box-sizing: border-box;
    height: 100px;
    line-height: 100px;
    position: relative;
    div{
      transition: transform 0.4s;
      position: absolute;
      top: 0;
      left: 0;
      height: 100%;
      width: 100%;
      background: #fff;
      color: #58B7FF;
      border: 1px solid #ccc;
      font-size: 40px;
      text-align: center;
    }
    &.pukeBg{
      cursor: pointer;
      div{
        background: url("") no-repeat center,#fff;
        &:first-child{
          z-index: 1;
          transform: rotateY( 0deg);
        }
        &:last-child{
          transform: rotateY( 180deg);
        }
      }
    }
    &.pukeNum{
      div{
        &:first-child{
          transform: rotateY( 180deg);
        }
        &:last-child{
          z-index: 1;
          transform: rotateY( 0deg);
        }
      }
    }
  }
}